1. Field of the Invention
The present disclosure relates to liquid handling and dispensing small amounts of liquids. The present disclosure relates to the field of diagnostics and a method, a system and an apparatus for filling a cavity with a liquid.
2. Introduction and Related Art
Handling of liquids in the microliter or milliliter range is important in many automated processes in biology, biochemistry, chemistry as well as in clinical or laboratory diagnostics and pharmaceutical research. Present liquid handling systems can handle a plurality of liquids in the same time and liquids are mixed, transferred and added in cavities or wells. Different types of cavities for liquid handling are known which can be used for handling single probes up to high throughput systems for handling large numbers of probes in parallel. For example, 96 well plates or well plates with other numbers of cavities are frequently used. Many liquid handling systems are highly automated and can handle a variety of liquids with high precision in short time intervals making these methods suitable for high throughput techniques.
Known systems have one or more pipettes or dispensing needles that allow the pipetting and dispensing of liquids in different cavities in series and/or in parallel.
In case several liquids are mixed in a cavity or several liquids have to be added to a single cavity, there is a risk that the cavities are overloaded and the liquid is spilled which may lead to contamination of neighbouring cavities and of the apparatus. Such contamination often requires expensive and extensive cleaning of the apparatus and can destroy valuable samples. Overfilling and subsequent contamination should be avoided. In many cases, however, a cavity is already filled with an unknown residual volume of liquid at the start of a liquid handling process. In this case, the residual volume has to be determined in order to avoid overfilling and spilling of the cavity.
Liquid level detectors are used in order to control the filling of cavities and to avoid overflow contamination and spilling of the liquids.
EP 0 913 671 (also published as U.S. Pat. No. 6,148,666) discloses a capacitive liquid level detector attached to a filling needle for determining if the filling needle is in contact with a liquid in the cavity.
DE 10 20060034245-A also describes a dispensing needle that may be equipped with a barometric or capacitive liquid level detection in order to detect the presence of a liquid in a cavity.
EP 2 031 499 discloses an apparatus and a method for detecting the level of liquid in a cavity to determine the amount of liquid present in the cavity. This method requiring the liquid level detector into the cavity until the detector comes into contact with the liquid surface.